1. Field of the Invention
The present invention relates to an actuator system for controlling a vehicular automated clutch and, in particular, relates to an actuator system utilizing an electric motor-controlled actuator and having a pressurized fluid-operated override mechanism for effecting rapid clutch movements not requiring precise control. In particular, a preferred embodiment of the present invention relates to an actuator system for a dry plate vehicular master clutch having an electric motor-controlled ball screw mechanism for precision positioning of the clutch, as is required during vehicle launch conditions, and having a solenoid-controlled pneumatic override actuator for rapidly disengaging the clutch and/or for moving the clutch from a fully disengaged position to the touch point or point of incipient engagement.
2. Description of the Prior Art
Automated vehicular master clutches and the controls and actuators therefor are known in the prior art, as may be seen by reference to U.S. Pat. Nos. 4,650,056; 4,638,898; 4,671,394; 4,712,658; 4,852,419; 4,874,070; 5,293,316; 5,314,050; 5,337,868 and 5,337,874, the disclosures of which are incorporated herein by reference. The automated clutches could be used with manual and/or fully or partially automated transmissions and could be used for dynamic shifting and/or vehicle launch (i.e., start-from-stop) operations, as may be seen by reference to U.S. Pat. Nos. 4,081,065; 4,361,060 and 4,648,290, the disclosures of which are incorporated herein by reference. As in known, vehicle launch and inching operations usually require more precise clutch control than is required during dynamic shifting operations.
Typically, the prior art devices included a clutch control member moved in one direction to cause engagement and in the opposite direction to cause disengagement of the controlled clutch.
While the prior art clutch actuator mechanisms were generally satisfactory, they were subject to improvement, as it was difficult to obtain both the rapid actuator movement desired for dynamic disengagement and/or movement to the touch point, and the delicate, fine control desired for inching and start-from-stop operations. While electric motor-based actuators, often associated with ball screw or ball ramp mechanisms, provided fine controls, they tended to be somewhat slow for disengagements and rapid movement to the touch point, and while pneumatic controls, even when using both fine and coarse valving, gave satisfactory speed, they were not as controllable as desired in certain situations.